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Collection with spatiotemporal indexation - Ideas and discussions ?

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cedreek

Collection with spatiotemporal indexation - Ideas and discussions ?

Hi Pharoers,

For a project I’m starting to prototype, I need collections where objects are inserted according to an index that is a spatiotemporal object.

The idea is that each time a person add an « information" in this collection, he does it a a given place and time and I want to be able to query the collection easily according to place or time (or both).

I’m hacking it right now but I wonder if people have ideas on that subject. I’m also interested in collection that that are indexed by the timestamp of the insertion.

For the implementation of spatiotemporal classe, I choose to use a ZTimestamp and a Geolocation object. Geolocation is quite simple and is responsible among other to get the timezone, but of courses coordinates (or eventually areas).

For the collection, I’m still wandering… Something like an OrderedCollection with another internal array to store associated spatiotemporal(s)… Will hack something but I’d love to hear others ideas.

Cheers,

Cédrik

nb: I really think a spatiotemporal class would be interesting as a general data structure today !

cedreek

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

A dictionary with keys being the timestamp or the spatiotemporal object would probably do it...
I think I’ll do that but I wonder if there are better solutions out there ^^.

Cheers,

Cédrik

Max Leske

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

There was talk about an ordered dictionary implementation IIRC a couple of months ago on this list.

I’ve attached an implementation I found in a thread from 2010 (may not work out of the box).

Cheers,
Max

> On 23 Apr 2016, at 13:46, Cédrick Béler <[hidden email]> wrote:
>
> A dictionary with keys being the timestamp or the spatiotemporal object would probably do it...
> I think I’ll do that but I wonder if there are better solutions out there ^^.
>
> Cheers,
>
> Cédrik

OrderedDictionary.st (11K) Download Attachment

alistairgrant

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by cedreek

I don't have a data structures book handy, but how about 3 SortedCollections? (Assuming 3 dimensions: latitude, longitude & time).

It would support a reasonably efficient binary search, and allow for areas and time ranges.

Regardless of which solution you choose I agree that it would be a useful general class, so please package it separately.

Cheers,
Alistair
(Sent from my mobile)

On 23/04/2016 1:47 PM, "Cédrick Béler" <[hidden email]> wrote:

A dictionary with keys being the timestamp or the spatiotemporal object would probably do it...
I think I’ll do that but I wonder if there are better solutions out there ^^.

Cheers,

Cédrik

cedreek

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by Max Leske

Thanks Max,

I’ve seen in Pharo 5 OrderedDictionary, OrderedPreservingDictionary and some others. I guess they have the same intent.

I was actually trying them right now :)

Cheers,

Cédrik

> Le 23 avr. 2016 à 13:57, Max Leske <[hidden email]> a écrit :
>
> There was talk about an ordered dictionary implementation IIRC a couple of months ago on this list.
>
> I’ve attached an implementation I found in a thread from 2010 (may not work out of the box).
>
> Cheers,
> Max
>
>
> <OrderedDictionary.st>
>
>> On 23 Apr 2016, at 13:46, Cédrick Béler <[hidden email]> wrote:
>>
>> A dictionary with keys being the timestamp or the spatiotemporal object would probably do it...
>> I think I’ll do that but I wonder if there are better solutions out there ^^.
>>
>> Cheers,
>>
>> Cédrik
>

cedreek

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by alistairgrant

Hi Alistair,

Thanks, this sounds like a nice suggestion.

I have to think about it.

Adding altitude would be also interesting in some cases but not as a start (quite limited usage).

When you say to package it separately, you’re talking about Geolocation, Spatiotemporal classes ? or also the collection ?

I can try something but I think this will deserve more « computational thinking » power than I have ^^

Cheers,

Cédrik

Le 23 avr. 2016 à 13:57, Alistair Grant <[hidden email]> a écrit :

I don't have a data structures book handy, but how about 3 SortedCollections? (Assuming 3 dimensions: latitude, longitude & time).
It would support a reasonably efficient binary search, and allow for areas and time ranges.
Regardless of which solution you choose I agree that it would be a useful general class, so please package it separately.
Cheers,
Alistair
(Sent from my mobile)

On 23/04/2016 1:47 PM, "Cédrick Béler" <[hidden email]> wrote:
A dictionary with keys being the timestamp or the spatiotemporal object would probably do it...
I think I’ll do that but I wonder if there are better solutions out there ^^.

Cheers,

Cédrik

Damien Pollet

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by cedreek

There are a lot of spatial access data structures: https://en.wikipedia.org/wiki/Spatial_database#Spatial_index

But for a prototype I don't think you care; a simple linear search should be ok for testing until you have thousands and thousands of records. It's probably more important to really explore what you need and how your constraints will influence the API (e.g. since we haven't invented teleportation yet, events for one person that are close in time are necessarily close in space)

On 23 April 2016 at 14:08, Cédrick Béler <[hidden email]> wrote:

Thanks Max,

I’ve seen in Pharo 5 OrderedDictionary, OrderedPreservingDictionary and some others. I guess they have the same intent.

I was actually trying them right now :)

Cheers,

Cédrik

> Le 23 avr. 2016 à 13:57, Max Leske <[hidden email]> a écrit :
>
> There was talk about an ordered dictionary implementation IIRC a couple of months ago on this list.
>
> I’ve attached an implementation I found in a thread from 2010 (may not work out of the box).
>
> Cheers,
> Max
>
>

> <OrderedDictionary.st>

>
>> On 23 Apr 2016, at 13:46, Cédrick Béler <[hidden email]> wrote:
>>
>> A dictionary with keys being the timestamp or the spatiotemporal object would probably do it...
>> I think I’ll do that but I wonder if there are better solutions out there ^^.
>>
>> Cheers,
>>
>> Cédrik
>

Damien Pollet
type less, do more [ | ] http://people.untyped.org/damien.pollet

SergeStinckwich

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by cedreek

On Sat, Apr 23, 2016 at 6:39 PM, Cédrick Béler <[hidden email]> wrote:
> Hi Pharoers,

Hi Cedrick, welcome back in the community.

> For a project I’m starting to prototype, I need collections where objects are inserted according to an index that is a spatiotemporal object.
>
> The idea is that each time a person add an « information" in this collection, he does it a a given place and time and I want to be able to query the collection easily according to place or time (or both).
>
> I’m hacking it right now but I wonder if people have ideas on that subject. I’m also interested in collection that that are indexed by the timestamp of the insertion.
>
> For the implementation of spatiotemporal classe, I choose to use a ZTimestamp and a Geolocation object. Geolocation is quite simple and is responsible among other to get the timezone, but of courses coordinates (or eventually areas).
>
> For the collection, I’m still wandering… Something like an OrderedCollection with another internal array to store associated spatiotemporal(s)… Will hack something but I’d love to hear others ideas.

You mean something like a timeseries ?
I start to work on a basic TimeSeries class quite similar to the one
you find in Panda:
http://pandas.pydata.org/pandas-docs/stable/timeseries.html

--
Serge Stinckwich
UCBN & UMI UMMISCO 209 (IRD/UPMC)
Every DSL ends up being Smalltalk
http://www.doesnotunderstand.org/

cedreek

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by Damien Pollet

There are a lot of spatial access data structures: https://en.wikipedia.org/wiki/Spatial_database#Spatial_index

But for a prototype I don't think you care; a simple linear search should be ok for testing

Yes sure but I keep that in mind for later « exploration ».

until you have thousands and thousands of records.

Potentially, on a person lifetime, adding hundreds information a day (and probably higher order of magnitude), I think we can easily reach millions of data quite easily :)

100 per day, in 10 years => 365 000

1000 per day in 100 years => 36 500 000

What I want is keeping track of all positions a person can have in his life (what can easily reach millions) and then rely on these « points » to index information added in the system.

It's probably more important to really explore what you need and how your constraints will influence the API

but I agree and I’ll work on that first.

(e.g. since we haven't invented teleportation yet, events for one person that are close in time are necessarily close in space)

yes… for now but in 50 years who knows :)

This remark is nevertheless interesting as a premise that can be used to check the validity of data (geospatial resolver are not that precise).

But yeah for now, an OrderedDic or another classic collection will do the job and will let me explore the API (and we might discuss it ^^).

I start this discussion as I thing this is one central modeling concept of what I want to do.

Cheers,

Cédrik

On 23 April 2016 at 14:08, Cédrick Béler <[hidden email]> wrote:
Thanks Max,

I’ve seen in Pharo 5 OrderedDictionary, OrderedPreservingDictionary and some others. I guess they have the same intent.

I was actually trying them right now :)

Cheers,

Cédrik

> Le 23 avr. 2016 à 13:57, Max Leske <[hidden email]> a écrit :
>
> There was talk about an ordered dictionary implementation IIRC a couple of months ago on this list.
>
> I’ve attached an implementation I found in a thread from 2010 (may not work out of the box).
>
> Cheers,
> Max
>
>

> <OrderedDictionary.st>

>
>> On 23 Apr 2016, at 13:46, Cédrick Béler <[hidden email]> wrote:
>>
>> A dictionary with keys being the timestamp or the spatiotemporal object would probably do it...
>> I think I’ll do that but I wonder if there are better solutions out there ^^.
>>
>> Cheers,
>>
>> Cédrik
>

--
Damien Pollet
type less, do more [ | ] http://people.untyped.org/damien.pollet

cedreek

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by SergeStinckwich

Hi Cedrick, welcome back in the community.

Thanks, I was not very far though ^^

For a project I’m starting to prototype, I need collections where objects are inserted according to an index that is a spatiotemporal object.

The idea is that each time a person add an « information" in this collection, he does it a a given place and time and I want to be able to query the collection easily according to place or time (or both).

I’m hacking it right now but I wonder if people have ideas on that subject. I’m also interested in collection that that are indexed by the timestamp of the insertion.

For the implementation of spatiotemporal classe, I choose to use a ZTimestamp and a Geolocation object. Geolocation is quite simple and is responsible among other to get the timezone, but of courses coordinates (or eventually areas).

For the collection, I’m still wandering… Something like an OrderedCollection with another internal array to store associated spatiotemporal(s)… Will hack something but I’d love to hear others ideas.

You mean something like a timeseries ?
I start to work on a basic TimeSeries class quite similar to the one
you find in Panda:
http://pandas.pydata.org/pandas-docs/stable/timeseries.html

I don’t really know, more a geospatial timeserie but It might be interesting. We’ll exchange on that subject I guess.

Cheers,

Cédrik

--
Serge Stinckwich
UCBN & UMI UMMISCO 209 (IRD/UPMC)
Every DSL ends up being Smalltalk
http://www.doesnotunderstand.org/

Damien Pollet

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by cedreek

On 23 April 2016 at 16:04, Cédrick Béler <[hidden email]> wrote:

1000 per day in 100 years => 36 500 000

What I want is keeping track of all positions a person can have in his life (what can easily reach millions) and then rely on these « points » to index information added in the system.

Sure, but 1) that's not a lot 2) do you even know if you need interactive stuff or if batch processing is ok?

Damien Pollet
type less, do more [ | ] http://people.untyped.org/damien.pollet

cedreek

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

Sure, but 1) that's not a lot

2) do you even know if you need interactive stuff or if batch processing is ok?

interactive I would say… but hard to be certain right now as it depends on design choices… do we cache ? do we aggregate past data ? extra indexes ? I’ll see later.

I want something simple, keep everything… and query according to time interval, areas (contexts)…

But yes for now this is pointless to look for something optimal and I’ll use a dictionary as it will be small at start.

Cheers,

Cédrik

--
Damien Pollet
type less, do more [ | ] http://people.untyped.org/damien.pollet

Esteban A. Maringolo

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

Maybe instead of having a Dictionary, you can use my History package [1].
It allows you to add elements to "the history", and the History class
will provide certain "lookup" strategies depending on how you want to
query it.

It is a trimmed down version of an utility class I used for years in
commercial products where the History contained thousands of elements.
This version uses linear search, my previous implementation used
binary search which was significantly faster with lots of elements in
the collection.

Of course it doesn't solve your spatial queries needs, I don't know if
there is something in Smalltalk for that other than the distance
between two coordinates[2], PostgreSQL 9.2 has some support for
"temporal" data/tables which you could combine with PostGIS if you
need to combine a spatial query with a temporal one [3].

Regards,

[1] http://www.smalltalkhub.com/#!/~emaringolo/History
[2] http://pastebin.com/ThKDXCKK
[3] http://clarkdave.net/2015/02/historical-records-with-postgresql-and-temporal-tables-and-sql-2011/
Esteban A. Maringolo

2016-04-23 12:13 GMT-03:00 Cédrick Béler <[hidden email]>:

>
>
> Sure, but 1) that's not a lot
>
> 2) do you even know if you need interactive stuff or if batch processing is
> ok?
>
>
> interactive I would say… but hard to be certain right now as it depends on
> design choices… do we cache ? do we aggregate past data ? extra indexes ?
> I’ll see later.
> I want something simple, keep everything… and query according to time
> interval, areas (contexts)…
>
> But yes for now this is pointless to look for something optimal and I’ll use
> a dictionary as it will be small at start.
>
> Cheers,
>
> Cédrik
>
>
>
>
> --
> Damien Pollet
> type less, do more [ | ] http://people.untyped.org/damien.pollet
>
>

cedreek

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

Hi Esteban,

Thanks a lot, I think I’ll try your History package, it seems to be a very good starting point (instead of hacking it myself).
I’ll try it soon.

Thanks for all the information ;)

Cheers,

Cédrik

> Le 23 avr. 2016 à 18:28, Esteban A. Maringolo <[hidden email]> a écrit :
>
> Maybe instead of having a Dictionary, you can use my History package [1].
> It allows you to add elements to "the history", and the History class
> will provide certain "lookup" strategies depending on how you want to
> query it.
>
> It is a trimmed down version of an utility class I used for years in
> commercial products where the History contained thousands of elements.
> This version uses linear search, my previous implementation used
> binary search which was significantly faster with lots of elements in
> the collection.
>
> Of course it doesn't solve your spatial queries needs, I don't know if
> there is something in Smalltalk for that other than the distance
> between two coordinates[2], PostgreSQL 9.2 has some support for
> "temporal" data/tables which you could combine with PostGIS if you
> need to combine a spatial query with a temporal one [3].
>
> Regards,
>
> [1] http://www.smalltalkhub.com/#!/~emaringolo/History
> [2] http://pastebin.com/ThKDXCKK
> [3] http://clarkdave.net/2015/02/historical-records-with-postgresql-and-temporal-tables-and-sql-2011/
> Esteban A. Maringolo
>
>
> 2016-04-23 12:13 GMT-03:00 Cédrick Béler <[hidden email]>:
>>
>>
>> Sure, but 1) that's not a lot
>>
>> 2) do you even know if you need interactive stuff or if batch processing is
>> ok?
>>
>>
>> interactive I would say… but hard to be certain right now as it depends on
>> design choices… do we cache ? do we aggregate past data ? extra indexes ?
>> I’ll see later.
>> I want something simple, keep everything… and query according to time
>> interval, areas (contexts)…
>>
>> But yes for now this is pointless to look for something optimal and I’ll use
>> a dictionary as it will be small at start.
>>
>> Cheers,
>>
>> Cédrik
>>
>>
>>
>>
>> --
>> Damien Pollet
>> type less, do more [ | ] http://people.untyped.org/damien.pollet
>>
>>
>

alistairgrant

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by cedreek

On Sat, Apr 23, 2016 at 02:13:22PM +0200, Cédrick Béler wrote:

> Hi Alistair,
>
> Thanks, this sounds like a nice suggestion.
>
> I have to think about it.
> Adding altitude would be also interesting in some cases but not as a start
> (quite limited usage).
>
> When you say to package it separately, you’re talking about Geolocation,
> Spatiotemporal classes ? or also the collection ?

My impression was that the Geolocation & Spatiotemperal classes already
exist (and presumably are already packaged), so I was thinking of the
collection class (which would have the geolocation and spatiotemperal as
dependencies).

> I can try something but I think this will deserve more « computational
> thinking » power than I have ^^

Me too, but having something is still better than nothing, and maybe
someone will provide ideas for improvements.

Cheers,
Alistair

Robert Withers

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by cedreek

Hi Cédrik,

Have you considered seeing if there are any Voronoi diagram packages in one of the repositories? I believe there is a fair bit of research into algorithms. You search use of spaciotemporal collated data sounds very interesting and there is a segment on computation over segments in this slide deck, that might be something, I don't know: http://graphics.stanford.edu/courses/cs368-06-spring/handouts/Delaunay_2.pdf. Certainly there is utility on the graphics side to use a 4D quadratic model (with GPU accel) and may well be modeled already in squeak/Pharo. Would't that be something!

Regards,
Robert

On 04/23/2016 01:29 PM, Cédrick Béler wrote:

> Hi Esteban,
>
> Thanks a lot, I think I’ll try your History package, it seems to be a very good starting point (instead of hacking it myself).
> I’ll try it soon.
>
> Thanks for all the information ;)
>
> Cheers,
>
> Cédrik
>
>
>> Le 23 avr. 2016 à 18:28, Esteban A. Maringolo <[hidden email]> a écrit :
>>
>> Maybe instead of having a Dictionary, you can use my History package [1].
>> It allows you to add elements to "the history", and the History class
>> will provide certain "lookup" strategies depending on how you want to
>> query it.
>>
>> It is a trimmed down version of an utility class I used for years in
>> commercial products where the History contained thousands of elements.
>> This version uses linear search, my previous implementation used
>> binary search which was significantly faster with lots of elements in
>> the collection.
>>
>> Of course it doesn't solve your spatial queries needs, I don't know if
>> there is something in Smalltalk for that other than the distance
>> between two coordinates[2], PostgreSQL 9.2 has some support for
>> "temporal" data/tables which you could combine with PostGIS if you
>> need to combine a spatial query with a temporal one [3].
>>
>> Regards,
>>
>> [1] http://www.smalltalkhub.com/#!/~emaringolo/History
>> [2] http://pastebin.com/ThKDXCKK
>> [3] http://clarkdave.net/2015/02/historical-records-with-postgresql-and-temporal-tables-and-sql-2011/
>> Esteban A. Maringolo
>>
>>
>> 2016-04-23 12:13 GMT-03:00 Cédrick Béler <[hidden email]>:
>>>
>>> Sure, but 1) that's not a lot
>>>
>>> 2) do you even know if you need interactive stuff or if batch processing is
>>> ok?
>>>
>>>
>>> interactive I would say… but hard to be certain right now as it depends on
>>> design choices… do we cache ? do we aggregate past data ? extra indexes ?
>>> I’ll see later.
>>> I want something simple, keep everything… and query according to time
>>> interval, areas (contexts)…
>>>
>>> But yes for now this is pointless to look for something optimal and I’ll use
>>> a dictionary as it will be small at start.
>>>
>>> Cheers,
>>>
>>> Cédrik
>>>
>>>
>>>
>>>
>>> --
>>> Damien Pollet
>>> type less, do more [ | ] http://people.untyped.org/damien.pollet
>>>
>>>
>

--
Robert
. .. ... ^,^

cedreek

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by alistairgrant

>
> My impression was that the Geolocation & Spatiotemperal classes already
> exist (and presumably are already packaged),

I don’t think so but if you know some packages, please tell me :)

> so I was thinking of the
> collection class (which would have the geolocation and spatiotemperal as
> dependencies).
>
>> I can try something but I think this will deserve more « computational
>> thinking » power than I have ^^
>
> Me too, but having something is still better than nothing, and maybe
> someone will provide ideas for improvements.
>

I’ll see what I’ll come up with and I’ll publish them.

Cheers,
Cédrik

>
> Cheers,
> Alistair
>
>

cedreek

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by Robert Withers

Hi Robert,

>
> Have you considered seeing if there are any Voronoi diagram packages in one of the repositories? I believe there is a fair bit of research into algorithms. You search use of spaciotemporal collated data sounds very interesting and there is a segment on computation over segments in this slide deck, that might be something, I don't know: http://graphics.stanford.edu/courses/cs368-06-spring/handouts/Delaunay_2.pdf. Certainly there is utility on the graphics side to use a 4D quadratic model (with GPU accel) and may well be modeled already in squeak/Pharo. Would't that be something!

Thanks for the links, very interesting read. I’ll have a closer look if I need to develop proper algorithms.

Cheers,
Cédrik

>
>
> Regards,
> Robert
>
>
> On 04/23/2016 01:29 PM, Cédrick Béler wrote:
>> Hi Esteban,
>>
>> Thanks a lot, I think I’ll try your History package, it seems to be a very good starting point (instead of hacking it myself).
>> I’ll try it soon.
>>
>> Thanks for all the information ;)
>>
>> Cheers,
>>
>> Cédrik
>>
>>
>>> Le 23 avr. 2016 à 18:28, Esteban A. Maringolo <[hidden email]> a écrit :
>>>
>>> Maybe instead of having a Dictionary, you can use my History package [1].
>>> It allows you to add elements to "the history", and the History class
>>> will provide certain "lookup" strategies depending on how you want to
>>> query it.
>>>
>>> It is a trimmed down version of an utility class I used for years in
>>> commercial products where the History contained thousands of elements.
>>> This version uses linear search, my previous implementation used
>>> binary search which was significantly faster with lots of elements in
>>> the collection.
>>>
>>> Of course it doesn't solve your spatial queries needs, I don't know if
>>> there is something in Smalltalk for that other than the distance
>>> between two coordinates[2], PostgreSQL 9.2 has some support for
>>> "temporal" data/tables which you could combine with PostGIS if you
>>> need to combine a spatial query with a temporal one [3].
>>>
>>> Regards,
>>>
>>> [1] http://www.smalltalkhub.com/#!/~emaringolo/History
>>> [2] http://pastebin.com/ThKDXCKK
>>> [3] http://clarkdave.net/2015/02/historical-records-with-postgresql-and-temporal-tables-and-sql-2011/
>>> Esteban A. Maringolo
>>>
>>>
>>> 2016-04-23 12:13 GMT-03:00 Cédrick Béler <[hidden email]>:
>>>>
>>>> Sure, but 1) that's not a lot
>>>>
>>>> 2) do you even know if you need interactive stuff or if batch processing is
>>>> ok?
>>>>
>>>>
>>>> interactive I would say… but hard to be certain right now as it depends on
>>>> design choices… do we cache ? do we aggregate past data ? extra indexes ?
>>>> I’ll see later.
>>>> I want something simple, keep everything… and query according to time
>>>> interval, areas (contexts)…
>>>>
>>>> But yes for now this is pointless to look for something optimal and I’ll use
>>>> a dictionary as it will be small at start.
>>>>
>>>> Cheers,
>>>>
>>>> Cédrik
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Damien Pollet
>>>> type less, do more [ | ] http://people.untyped.org/damien.pollet
>>>>
>>>>
>>
>
> --
> Robert
> . .. ... ^,^
>
>

Esteban A. Maringolo

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by cedreek

2016-04-23 14:29 GMT-03:00 Cédrick Béler <[hidden email]>:
> Hi Esteban,
>
> Thanks a lot, I think I’ll try your History package, it seems to be a very good starting point (instead of hacking it myself).
> I’ll try it soon.
>
> Thanks for all the information ;)

Feel free to modify it if you want, as long as you preserve it's
original output, of course :)

Regards!

Esteban A. Maringolo

Henrik Sperre Johansen

Re: Collection with spatiotemporal indexation - Ideas and discussions ?

In reply to this post by cedreek

I agree with Alistair; a pattern like EventSourcing works well for building efficient query structures for a set of data along different as-yet-to-be-determined dimensions.

In Pharo terms, you can implement this using a EventStream that announces new entries, then install announcement handlers each updating a dimension-specific data structure.

Also makes it easy to add new dimensions if you find you need them; simply add a new handler and replay the EventStream (with the other handlers temporarily disabled).

Cheers,

Henry

On 23 Apr 2016, at 2:13 , Cédrick Béler <[hidden email]> wrote:

Hi Alistair,

Thanks, this sounds like a nice suggestion.

I have to think about it.
Adding altitude would be also interesting in some cases but not as a start (quite limited usage).

When you say to package it separately, you’re talking about Geolocation, Spatiotemporal classes ? or also the collection ?
I can try something but I think this will deserve more « computational thinking » power than I have ^^

Cheers,

Cédrik

Le 23 avr. 2016 à 13:57, Alistair Grant <[hidden email]> a écrit :

I don't have a data structures book handy, but how about 3 SortedCollections? (Assuming 3 dimensions: latitude, longitude & time).
It would support a reasonably efficient binary search, and allow for areas and time ranges.
Regardless of which solution you choose I agree that it would be a useful general class, so please package it separately.
Cheers,
Alistair
(Sent from my mobile)

On 23/04/2016 1:47 PM, "Cédrick Béler" <[hidden email]> wrote:
A dictionary with keys being the timestamp or the spatiotemporal object would probably do it...
I think I’ll do that but I wonder if there are better solutions out there ^^.

Cheers,

Cédrik

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